The toxins from Conus geographus venom have been purified. These fall into four classes; two act on the peripheral neuromuscular system and two act on the central nervous system of vertebrates. The first class has been most well characterized; primary sequences of three homologous toxins of this class have been determined, and a preliminary secondary sequence assignment has been completed. These are all basic peptides of 13-15 amino acids, with two disulfide bonds and blocked carboxyl terminii. In the coming year, we plan to determine which structural determinants of the peptides are important for biological activity. Primary sequence determination of the other classes of toxins will also be carried out where feasible.